Manufacturing cost and production cost considerations may dictate that a direct view television receiver design be utilized to form the basis of a projection display receiver. Such a projection display receiver design is predicated upon minimum changes to the basic receiver design such that manufacturing, test and alignment procedures are essentially unchanged.
In a projection type video display, the raster distortions associated with a direct view display may be exacerbated by the use of a curved face plate CRT and the magnification inherent in the optical projection path. The use of a curved face plate CRT may offer benefits in a reduction of projection path length, and may also enable optical imaging simplification.
The use of an auxiliary deflection correction coil is known in projection display apparatus, it is also known that independent control of raster edges be provided. However, the combination of direct view deflection waveform correction, and the requirement to achieve more stringent convergence specifications associated with a projected raster result in the application of inventive deflection correction methods.